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Today's Sponsor: FireHydrant

Stuck in incident management deja vu? Stop simply putting out fires and start improving reliability with a full-cycle incident management platform.

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Creating a 2D physics engine from scratch in Javascript

Published: 12 November 2022
Tags: graphics, javascript

Ailef discusses how to write a toy 2d physics engine that supports basic forces, collisions and constraints (joints) for circle-shaped objects, as well as a renderer to make it all visible.
Some highlights:

• Verlet integration is a method to compute an approximation for the motion of an object at discrete intervals of time
• Constraints tell the physics engine where an object shouldn't be located and collisions are just constraints that tell the engine two objects can't overlap
• Handling different shapes with constraints is difficult

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A Complete Guide to Lock Convoys

Published: 28 November 2022
Tags: algorithms, cpu, os

Dave Kilian presents lock convoys, which are a problem that causes throughput to collapse in high-performance multithreaded networked systems. The problem arises from the interplay between the designs of code, the CPU, the operating system kernel, and the way locks are implemented in software.
Some highlights:

• "A convoy is a persistent chain reaction of waiting that can occur in any queuing system"
• One small issue can lead to a huge time lag
• If locks have a bunch of waiting threads queued up, a convoy is likely to happen if there's a timing issue

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3 mistakes I’ve made at the beginning of an incident (and how not to make them)

Published: 29 June 2022
Tags: infosec, management, sponsored

FireHydrant highlights three mistakes you should avoid making at the start of a security incident.

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Simple Refinement of Anonymous Sum Types in Pattern Matches

Published: 26 November 2022
Tags: type theory

Ayaz Hafiz "share[s] a simple method to achieve type refinement, a-la flow typing, in a language with anonymous sum types and pattern matching".
Some highlights:

• Type refinement refers to the narrowing of a value's type based on the control flow of a program
• The method is derived from OCaml's conversion bindings of polymorphic variants and supports compilation of anonymous sums to non-uniform memory layouts
• There's a lot of academic jargon, but the principles are pretty simple

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